Transparent conductive oxide (TCO) materials are components in a variety of devices including flat-panel displays, photovoltaic cells, smart windows, light emitting diodes, and optical waveguides. The performance of a TCO may be related both to the conductivity of the TCO and to the optical transparency of the TCO. According to the Drude model, conductivity is related to the carrier concentration and the mobility of the carrier. However, with increased carrier concentration in a material, there may be decrease in optical transparency. To increase conductivity without decreasing optical transparency, the carrier mobility in a material should be increased without increasing carrier concentration.
Currently, tin-doped indium oxide (ITO) is a transparent conductive oxide material for commercial applications. ITO has good optical properties and good electrical properties. Another material that has been considered is indium oxide doped with molybdenum. Using Mo-doped indium oxide can provide a TCO material that has a high carrier mobility of about 70 cm2V−1s−1. Combinatorial deposition and analytical techniques have been applied to sputtered films of In2O3 doped with titanium up to 7 atomic percent concentration. These sputtered films were determined to have a maximum mobility of 83.3 cm2V−1s−1 at a titanium doping of 1.7 atomic percent and a conductivity of 6260 Ω−1cm−1 for titanium doping of 2.8 atomic percent. The optical transparency for these sputtered Ti-doped indium oxide films has been measured to be greater than 85% over a wide spectral range. In addition, for these Ti-doped indium oxide films with titanium doping concentrations between 1 and 3 atomic percent, one carrier is generated for every titanium atom.